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Mystery of Martian Dust in Space

svetz

Works in theory! Practice? That's something else
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NASA's Juno spacecraft flew through the dust cloud en route to Jupiter between 2011 and 2016. Dust grains smashed into Juno at about 10,000 mph, chipping off submillimeter pieces of spacecraft. Juno's oversized solar arrays turned out to be excellent dust detectors, registering as many as 200 hits per day.

Ironically, the sandblasting allowed researchers to map the cloud for the first time. One theory of Zodiacal Light held that asteroids were responsible. Yet, as Juno flew through the asteroid belt toward Jupiter, impact rates sharply dropped, sometimes to zero. Asteroids were not the answer. Instead, they realized, the dust must be coming from Mars. Orbital elements of the dust grains essentially match that of the Red Planet.

But how does this dust escape? During storms, dust is sometimes launched to very high altitudes in the Martian atmosphere; researchers call it 'rocket dust'. However, leaving Mars requires overcoming escape velocity (~5 km/s), and even rocket dust has trouble doing that. Dust grains would have an easier time launching from Phobos and Deimos; however, those small moons don't produce enough dust to explain the Zodiacal Light.

So, there's still a mystery here. Mars has the dust, but researchers haven't yet figured out how Mars delivers it. Lead author John Leif Jørgensen (Technical University of Denmark) and colleagues hope other scientists will help them solve this final piece of the puzzle.
 
I'm still trying to figure out how the planets revolving around the sun are all pretty close to being in the same plane, especially when planets' natural satellites seem to diverge so much from equatorial orbits.
 
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